What is the Autism Spectrum?
Autism is a spectrum disorder. In other words, the symptoms and characteristics of autism can present themselves in a wide variety of combinations, from mild to severe. Although autism is defined by a certain set of behaviors, children and adults can exhibit any combination of the behaviors in any degree of severity. Two children, both with the same diagnosis, can act very differently from one another and have varying skills.
Therefore there is no standard "type" or "typical" person with autism.
Parents may hear different terms used to describe children within this spectrum, such as: autistic-like, autistic tendencies, autism spectrum, high-functioning or low-functioning autism, more-abled or less-abled.
Most important to understand is, whatever the diagnosis, children can learn and function productively and show gains from appropriate education and treatment.
Autistic Disorder: Impairments in social interaction, communication, and imaginative play prior to age 3 years. Stereotyped behaviors, interests and activities.
Asperger's syndrome: Characterized by impairments in social interactions and the presence of restricted interests and activities, with no clinically significant general delay in language, and testing in the range of average to above average intelligence.
Pervasive Developmental Disorder: Not Otherwise Specified (commonly referred to as atypical autism); a diagnosis of PDD-NOS may be made when a child does not meet the criteria for a specific diagnosis, but there is a severe and pervasive impairment in specified behaviors.
Rett's Disorder: Progressive disorder which, to date, has occurred only in girls. Period of normal development and then loss of previously acquired skills, loss of purposeful use of the hands replaced with repetitive hand movements beginning at the age of 1 - 4 years.
Childhood Disintegrative Disorder: Normal development for at least the first 2 years, significant loss of previously acquired skills.
Source: Autism Society of America, January 2000